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Re: X-Ray Transformer - 50kV - FOR SALE

Original poster: Ben McMillen <spoonman534@xxxxxxxxx>

   This transformer came out of a geolgical sample setup..
The transformer itself is water cooled (was) and the front
panel had a timer for 0 - 24 hours exposure. The following
was sent to me by Godfrey Loudner back when I first posted
this on the list: (it seems that it's rated for 50mA, not
10 like I had originally thought.. )

In the x-ray tube application, 220 volts is connected to P1
and P2. One
to keep in mind that an x-ray transformer is specifically
designed for
loading with an x-ray tube. In your case this probably
means that the
transformer will apply 50kV at a current of 50mA across the
x-ray tube.
you were to apply 220 volts to the primary, with no load on
the HV
side, the
voltage developed could be much in excess of 50kV. The
amount of excess
depends upon the quality of the transformer. One could use
a sphere gap
to determine the amount of primary voltage necessary to
produce 50kV on
high side. For the time being, I would apply no more than
180 volts to

You must ballast the primary as your transformer is not
Without a ballast, the short circuit current on the high
side could be
tremendous. Don't be fooled into thinking of your
transformer as a
50mA sort of NST.

Of the three leads on the single HV terminal, one supplies
high voltage
the x-ray tube cathode and the other two supply LV to the
x-ray tube
filament. The LV for the filament rides the HV line. If you
connect all
three of these leads together, you will short out a
that is located inside the tank. Any terminal marked with
an F has to
with supplying the primary of a filament transformer.

I have not personally worked with x-ray transformers having
only one HV
port. My experience is limited to those with two or more HV
ports. I am
guessing that there are two primary coils and two secondary
coils. The
secondary coils must be connected in parallel with two
common leads
going to
the single HV terminal, and the other two common leads
going to the
Then the high voltage can be taken from the single HV
terminal and the

If you simply want a DC high voltage charging source, then you need to do nothing more. Except you need to to know if the rectifier system uses valve-tubes. Valve-tubes have filaments, so you will have to supply the proper terminals to activate the filament transformers for the valve-tubes. All filament transformers are inside the tank. If the rectifier system uses diode sticks, then no filament transformers are involved in the rectifier system. If you arc the transformer in the DC mode, you will destroy the rectifier system.

If you want an AC high voltage source, you will have to
remove the
transformer from the tank. The rectifier system and all
transformers will have to be removed. Do not cut any HV
lead to the
transformer while modifying the transformer. Once the
transformer is
for close up study, it should be clear what you will have
to do. If
not, you
can always ask for help.

A transformer that is very similar to yours can be seen at
http://allencoilpage.home.att.net. I am sure that Allen
would be happy
advise you about your transformer.

Godfrey Loudner

So there you have it..

Coiling In Pittsburgh
Ben McMillen

--- Tesla list <tesla@xxxxxxxxxx> wrote:
> Original poster: DRIEBEN@xxxxxxxxxxxxxxx
> Hi Ben, all,
> 50 kV seems a bit low voltage for an x-ray transformer.
> Are you sure that this transformer was for x-ray applica-
> tion? I think even dental x-ray units are usually around
> 70 kV at 5 to 10 mA. Most medical x-ray units are rated
> at >100 kV and several hundred mAs. Just curious...
> David Rieben
> ----- Original Message -----
> From: Tesla list <tesla@xxxxxxxxxx>
> Date: Wednesday, March 9, 2005 9:01 am
> Subject: X-Ray Transformer - 50kV - FOR SALE
>  > Original poster: Ben McMillen <spoonman534@xxxxxxxxx>
>  >
>  > Hi all,
>  >    I have an x-ray transformer for sale that I picked
> up a
>  > few years back, hoping to use the core material to
> make a
>  > good PSU for a coil. I haven't been able to use it and
> it's
>  > been taking up space, so I'm gonna sell it..
>  >
>  > The output is rated for 50kV (at maybe 10mA max, I
> think)
>  > so some rework would probably be required. If you want
> the
>  > ENTIRE transformer, you'll have to come and pick it up
> (I'm
>  > not going to try to deal with shipping all that oil).
>  > Otherwise, the core is up for sale (good core
> material, I
>  > think some HV rectifiers in there too, mabye t00b)
> which I
>  > will drain, pack, and ship..
>  >
>  > Please email me off list if interested..
>  >
>  > Here are a few pictures..
>  >
>  >
> http://medix.homeip.net/cpg132/thumbnails.php?album=142
>  >
>  > Coiling In Pittsburgh
>  > Ben McMillen
>  >
>  >
>  >
>  >